A second alternative to standard statistical pooling is the use of higher-order statistics (skewness and kurtosis) [1]}. Skewness is a measure of the asymmetry of a distribution with respect to its mode, while the kurtosis measures its “tailedness”. The authors did not obtain any consistent improvement compared to using merely first and second statistics, as in standard statistical pooling. Recently (and concurrently to our work) a set of alternative pooling methods were examined in [2]}. The authors show that the use of second order statistics is more effective compared to first order, while they also perform experiments with using the full covariance matrix, without showing improvements over the standard statistical pooling. Their work is close to ours, although we differ in several ways, such as in the suggested pooling method and in the several implementation details (e.g. instead of covariances we propose frequency-dependent channel-wise correlation matrices).
